Method of testing oh



y 24, v. A. SCHOENBERG Re. 19,255

METHOD OF TESTING OIL Original Filed July 24, 1953 In yen for 15 7/2726. 50/2 06/219659 Reissued July 24, 1934 UNITED STATES PATENT OFFICEMETHOD OF TESTING OIL' Virgil A. Schoenberg, Niles Center, 111.,assignor to Light Research Corporation, Niles Center,

III., a corporation of Illinois 4 Claims.

This invention relates to an improved method for preparing samples ofliquid for testing purposes. 4 1

The main objects of this invention are to provide an improved method fordetermining the degree of contamination of a liquid by means of lightpassing therethrough; to provide an improved method of preparing asample of the liquid to be tested; to provide a simplified means forforming a film of predetermined depth of the liquid to be tested; and toprovide an improved liquid testing slide that can be rapidly and readilymanipulated with a high degree of accuracy. I

A specific embodiment of this invention is shown in the accompanyingdrawing in which:

Figure 1 is a diagrammatic lay-out comprising the three principalelements of a liquid testing apparatus.

Fig. 2 is a perspective view of a testing slide showing a straightedgeas used in wiping the same to form a film of liquid. 7

Fig.- 3 is a sectional view taken through the center of the testingslide and illustrating a preferred construction of the same.

In the form shown in the drawing my improved liquid testing devicecomprises a slide formed of rectangular base plate 1 having secured onone face thereof a cover sheet 2 of predetermined thickness and having acentrally disposed aperture 3; and a straightedge wiper 4 of suitablesize to wipe substantially the entire surface of the slide.

The base plate 1 maybe made of any suitable material that is pervious tolight, but is preferably made from glass. The cover sheet 2 may be madeof any suitable, preferably opaque, material of uniform predeterminedthickness that will provide a plane outer surface, and the straightedgemay be made of any substantially rigid material suitable to be providedwith and retain a straight angular edge.

The aperture 3 in the cover plate 2 provides a recessed or countersunkportion in'the testing slide in which the sample of the liquid to betested is placed, and, because of the preferably opaque nature of thecover plate 2, light passing through the slide is confined to thecountersunk portion. It is understood that the slide may be made from asingle piece of material into which the countersunk portion is cut orground. In such cases the body of the slide in which the countersunkportion is formed is made opaque and only the countersunk portion of theslide is 55 made so as to be pervious to light.

.The art of determining the density and the contaminating content offluids by means of light sensitive apparatus is well known, and theusual method is to interpose a sample of the fluid to be tested betweena light source of known intensity and a light sensitive device such as aphotronic cell or a photoelectric cell, whereby a meter is caused toindicate the relative amount of light penetrating the fluid beingtested, the amount of penetrating light having .a definite relation tothe contaminating content of the fluid. In such apparatus the fluid isusually caused to flow through a channel arranged between the lightsource and the light sensitive apparatus. However, such apparatus isbulky and intricate and requires a relatively large quantity of thefluid to be tested in order to obtain satisfactory results.

In the use of my invention the apparatus shown is arranged in a verticalplane as illustrated in Fig. 1, the light source 5 being positionedabove and the light sensitive device 6 being positioned below thetesting slide which is in Fig. 1 designated by the numeral '7. Thisapparatus can be arranged in a convenient compact form and provided withsuitable means not shown, upon or into which the slide 7 is placed whena test is to be made. The meter 8 which indicates the relative amount oflight passing through the sample being tested is acg5 tuated by thelight sensitive device 6 and is positioned in any suitable locationwhere it can be conveniently observed by the operator. 7

The calibration of the meter or indicator 8 is preferably in terms thatdirectly indicate the relative amount of contaminating substance in thesample so that the operator can make an instant determination of thecondition of the liquid under test without having to refer to aconversion chart or table. Forexamplc, the cali- 5 bration for a liquidused in a certain process or operation would be in terms directlyindicating the condition or suitability of that liquid for continued usein that operation or process.

The operation of the apparatus shown consists in placing a quantity ofthe fluid to be tested in the counter-sunk portion of the test slidewhich is formed by the aperture 3 in the cover sheet 2 and then wipingthe surface of the cover sheet with the straightedge so as to remove anyexcess liquid therefrom and f rm a plane surface on the liquid in thecounter-sunk portion 9. The slide is then inserted into the testingapparatus in a level horizontal position, and the action of no gravityis relied upon to maintain the liquid sample in a proper condition onthe slide.

In testing the density or the relative amount of contaminating matter ina liquid, it is essential that the test sample be of a definite,predetermined depth or thickness, since the intensity of the lightsource and the calibration of the meter are arranged to indicate acertain definite amount of light passing through a proof or basic sampleof the liquid being tested, and the change of density or degree ofcontamination of other samples of liquid are indicated by a deviation onthe meter from the normal or basic reading.

In testing liquids it is preferable to have the test sample in the formof a film, in order that the intensity of the light source need not beso great. However, in apparatus now in use it is difiicult to obtain asample film of a predetermined thickness without a complicated andcostly arrangement of glass plates or the like between which a stream ofliquid of predetermined depth is forced. With my improved device a smallsample of the liquid to be tested is readily spread into a film of thedesired predetermined thickness through the action of the straightedgeas it wipes, across the plane surface of the test plate and wipes orplanes off the excess liquid, the thickness of the film being determinedby the thickness of the cover sheet 2, which is preferably cemented ontothe base plate 1. With such a device the thickness of the test samplesor films is always constant and the results of the test are exceedinglyaccurate.

The quantity of liquid placed on the slide is always greater than isnecessary to form the film and the excess liquid is removed by thewiper.

The principal advantages of my invention reside in the simplicity of theapparatus involved and the rapidity with which a small sample of theliquid to be tested can be prepared for testing. For example, in thetesting of oil in the crank case of a motor, it is only necessary toobtain a few drops of the oil, drop them into the counter-sunk portionof the test plate, wipe away the surplus oil and form a plane surface onthe liquid in the counter-sunk portion by means of the straightedge, andthen insert the slide into the testing apparatus, after which a readingon the meter can be instantly obtained. With the previous testingequipments it was necessary to use alarge sample of the liquid to betested in order that the same could be caused to flow in a streamthrough the testing apparatus and reliable results obtained.

Although but one specific embodiment of this vention has been hereinshown and described, it will be understood that details of theconstruction shown may be altered or omitted without departing from thespirit of this invention as defined by the following claims.

I claim:

1. The method of testing oils which consists in forming a .film of oilof predetermined thickness on a transparent slide by overfillingadepression of uniform depth in the surface of said slide with the oil tobe tested and wiping the surface of said slide with a straightedge toremove the excess oil above the plane of the surface of said slide andprovide a plane surface on the oil in said depression, placing saidslide in a horizontal position between a light source and a lightsensitive device, and measuring the light passing through the oil film.

- 2. The method of testing liquids which con sists in forming a film ofthe liquid of predetermined thickness on a transparent slide by overfilling a depression of uniform depth in the surface of said slidewiththe liquid to be tested and wiping the surface of said slide with astraight edge to remove the excess liquid above the plane of the surfaceof said slide and provide a plane surface on the liquid in said-depression, placing said slide in a horizontal position directlybetween a light source and a light receptive device, and measuring theemergent light. V

3. The method of testing oils which consists in forming a film of oil ofpredetermined thickness on a transparent slide by overfilling adepression of uniform depth in the surface of said slide with the oil tobe tested and wiping the surface of said slide with a straightedge toremove the excess oil above the plane of the surface of said slide andprovide a plane surface on the oil in said depression, placing saidslide between a light source and a light sensitive device, and measuringthe light passing through the oil film.

4. The method of testing liquids which consists in forming a film of theliquid of predetermined thickness on a transparent slide by overfillinga depression of uniform depth in the surface of said slide with theliquid to be tested and wiping the surface of said slide witha-straightedge to remove theexcess liquid above the plane of the surfaceof said slide and provide a plane surface on the liquid in saiddepression, placing said slide directly between a light source and alight receptive device, and measuring the emergent light.

VIRGIL' A. SCHOENBERG.

